GD32 开发笔记

0x01 GPIO时钟使能的坑

使用GD32的GPIO引脚来控制 74HC595 ，发现引脚一直无法控制，始终输出3.3v，初始化环节应该是出了问题。用通俗的话来说，就是点灯点不亮

排查了MCU、光耦隔离芯片、被强行上拉等问题，最后发现是GD的GPIO时钟使能问题。

以下是错误使用方法：

    rcu_periph_clock_enable(RCU_SER | RCU_SCK);

修改为以下方法即可：

    rcu_periph_clock_enable(RCU_SER);
    rcu_periph_clock_enable(RCU_SCK);

日后想必也会经常需要验证GD32，留个点灯函数在这里

rcu_periph_clock_enable(RCU_GPIOC);
gpio_mode_set(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN_13);
gpio_output_options_set(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_13);

gpio_bit_set(GPIOC,GPIO_PIN_13);
gpio_bit_reset(GPIOC,GPIO_PIN_13);

0x02 微秒级延时函数

systick.c

#include "gd32f1x0.h"
#include "systick.h"

volatile static uint32_t delay;

#include "systick.h"

volatile static float count_1us = 0;
volatile static float count_1ms = 0;

void delay_decrement(void)
{
    if (0U != delay){
        delay--;
    }
}

void systick_config(void)
{
	/* systick clock source is from HCLK/8 内部时钟的108M/8分频 */
    systick_clksource_set(SYSTICK_CLKSOURCE_HCLK_DIV8);
    count_1us = (float)SystemCoreClock/12000000;//延时1us需要的时钟数量 108M/8M = 13.5 
    count_1ms = (float)count_1us * 1000;//延时1ms需要的时钟数量 108M/8M *1000= 13500 
}

void delay_1us(uint32_t count)
{
    uint32_t ctl;
    SysTick->LOAD = (uint32_t)(count * count_1us);
    SysTick->VAL = 0x0000U;
    SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;
    do{
        ctl = SysTick->CTRL;
    }while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));
    SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
    SysTick->VAL = 0x0000U;
}

void delay_1ms(uint32_t count)
{
    uint32_t ctl;
    SysTick->LOAD = (uint32_t)(count * count_1ms);
    SysTick->VAL = 0x0000U;
    SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;
    do{
        ctl = SysTick->CTRL;
    }while((ctl&SysTick_CTRL_ENABLE_Msk)&&!(ctl & SysTick_CTRL_COUNTFLAG_Msk));
    SysTick->VAL = 0x0000U;
}

systick.h

#ifndef SYSTICK_H
#define SYSTICK_H

#include <stdint.h>

void systick_config(void);
void delay_1ms(uint32_t count);
void delay_1us(uint32_t count);
void delay_decrement(void);

#endif 

0x03 串口初始化的坑

串口初始化常常使用到的是PA9.PA10，但这两个引脚有些时候并不太方便去飞线，相较于GD32F130C8T6，串口1的PA2、PA3引脚就在MCU边角上，方便调试

#define EVAL_COM                        USART1
#define EVAL_COM_CLK                    RCU_USART1

#define EVAL_COM_TX_PIN                 GPIO_PIN_2
#define EVAL_COM_RX_PIN                 GPIO_PIN_3

#define EVAL_COM_GPIO_PORT               GPIOA
#define EVAL_COM_GPIO_CLK                RCU_GPIOA
#define EVAL_COM_AF                      GPIO_AF_1


void gd_eval_com_init(uint32_t COM)
{
    /* enable GPIO clock */
    uint32_t COM_ID = 0U;
    if(EVAL_COM0==COM){
        COM_ID = 0U;
    }

    rcu_periph_clock_enable( EVAL_COM_GPIO_CLK);
    rcu_periph_clock_enable(EVAL_COM_CLK);

    /* connect port to USARTx_Tx */
    gpio_af_set(EVAL_COM_GPIO_PORT, EVAL_COM_AF,EVAL_COM_TX_PIN);

    /* connect port to USARTx_Rx */
    gpio_af_set(EVAL_COM_GPIO_PORT, EVAL_COM_AF,EVAL_COM_RX_PIN);

    /* configure USART Tx as alternate function push-pull */
    gpio_mode_set(EVAL_COM_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,EVAL_COM_TX_PIN);
    gpio_output_options_set(EVAL_COM_GPIO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ,EVAL_COM_TX_PIN);

    /* configure USART Rx as alternate function push-pull */
    gpio_mode_set(EVAL_COM_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,EVAL_COM_RX_PIN);
    gpio_output_options_set(EVAL_COM_GPIO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ,EVAL_COM_RX_PIN);

   /* USART configure */
    usart_deinit(COM);
    usart_baudrate_set(COM,9600U);
    usart_transmit_config(COM, USART_TRANSMIT_ENABLE);
    
    usart_receive_config(COM, USART_RECEIVE_ENABLE);
    usart_enable(COM);
}